2 * pixel format descriptor
3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #ifndef AVCODEC_PIXDESC_H
23 #define AVCODEC_PIXDESC_H
27 #include "libavutil/intreadwrite.h"
30 typedef struct AVComponentDescriptor{
31 uint16_t plane :2; ///< which of the 4 planes contains the component
34 * Number of elements between 2 horizontally consecutive pixels minus 1.
35 * Elements are bits for bitstream formats, bytes otherwise.
37 uint16_t step_minus1 :3;
40 * Number of elements before the component of the first pixel plus 1.
41 * Elements are bits for bitstream formats, bytes otherwise.
43 uint16_t offset_plus1 :3;
44 uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
45 uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
46 }AVComponentDescriptor;
49 * Descriptor that unambiguously describes how the bits of a pixel are
50 * stored in the up to 4 data planes of an image. It also stores the
51 * subsampling factors and number of components.
53 * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
54 * and all the YUV variants) AVPixFmtDescriptor just stores how values
55 * are stored not what these values represent.
57 typedef struct AVPixFmtDescriptor{
59 uint8_t nb_channels; ///< The number of components each pixel has, (1-4)
62 * Amount to shift the luma width right to find the chroma width.
63 * For YV12 this is 1 for example.
64 * chroma_width = -((-luma_width) >> log2_chroma_w)
65 * The note above is needed to ensure rounding up.
67 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
70 * Amount to shift the luma height right to find the chroma height.
71 * For YV12 this is 1 for example.
72 * chroma_height= -((-luma_height) >> log2_chroma_h)
73 * The note above is needed to ensure rounding up.
75 uint8_t log2_chroma_h;
77 AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
80 #define PIX_FMT_BE 1 ///< big-endian
81 #define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
82 #define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
85 * The array of all the pixel format descriptors.
87 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
90 * Reads a line from an image, and writes to \p dst the values of the
91 * pixel format component \p c.
93 * @param data the array containing the pointers to the planes of the image
94 * @param linesizes the array containing the linesizes of the image
95 * @param desc the pixel format descriptor for the image
96 * @param x the horizontal coordinate of the first pixel to read
97 * @param y the vertical coordinate of the first pixel to read
98 * @param w the width of the line to read, that is the number of
99 * values to write to \p dst
100 * @param read_pal_component if not zero and the format is a paletted
101 * format writes to \p dst the values corresponding to the palette
102 * component \p c in data[1], rather than the palette indexes in
103 * data[0]. The behavior is undefined if the format is not paletted.
105 static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
106 const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component)
108 AVComponentDescriptor comp= desc->comp[c];
109 int plane= comp.plane;
110 int depth= comp.depth_minus1+1;
111 int mask = (1<<depth)-1;
112 int shift= comp.shift;
113 int step = comp.step_minus1+1;
114 int flags= desc->flags;
116 if (flags & PIX_FMT_BITSTREAM){
118 init_get_bits(&gb, data[plane] + y*linesize[plane], linesize[plane]*8);
119 skip_bits_long(&gb, x*step + comp.offset_plus1-1);
122 int val = show_bits(&gb, depth);
123 if(read_pal_component)
124 val= data[1][4*val + c];
125 skip_bits(&gb, step);
129 const uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
133 if(flags & PIX_FMT_BE) val= AV_RB16(p);
134 else val= AV_RL16(p);
135 val = (val>>shift) & mask;
136 if(read_pal_component)
137 val= data[1][4*val + c];
145 * Writes the values from src to the pixel format component c of an
148 * @param src array containing the values to write
149 * @param data the array containing the pointers to the planes of the
150 * image to write into. It is supposed to be zeroed.
151 * @param linesizes the array containing the linesizes of the image
152 * @param desc the pixel format descriptor for the image
153 * @param x the horizontal coordinate of the first pixel to write
154 * @param y the vertical coordinate of the first pixel to write
155 * @param w the width of the line to write, that is the number of
156 * values to write to the image line
158 static inline void write_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
159 const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
161 AVComponentDescriptor comp = desc->comp[c];
162 int plane = comp.plane;
163 int depth = comp.depth_minus1+1;
164 int step = comp.step_minus1+1;
165 int flags = desc->flags;
167 if (flags & PIX_FMT_BITSTREAM) {
168 int skip = x*step + comp.offset_plus1-1;
169 uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
170 int shift = 8 - depth - (skip&7);
173 *p |= *src++ << shift;
179 int shift = comp.shift;
180 uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
183 if (flags & PIX_FMT_BE) {
184 uint16_t val = AV_RB16(p) | (*src++<<shift);
187 uint16_t val = AV_RL16(p) | (*src++<<shift);
195 #endif /* AVCODEC_PIXDESC_H */